Enhancement of Bloodstains on Washed Clothing Using Luminol and LCV Reagents

Luminol and LCV are commonly used reagents to develop latent bloodstains on evidence and at crime scenes. Luminol was first used to detect latent bloodstains in 1937 (1). Since that time the use of luminol has become very popular with many law enforcement agencies. The application of luminol creates a blue/green color chemiluminescence from its reaction with hemoglobin. Observation and subsequent documentation of latent bloodstain reactions with luminol require near to total darkness for best results. Leuco-crystal Violet (LCV) is another commonly used latent blood reagent for evidence and crime scenes. Bodziak (2) reports that the Federal Bureau of Investigation laboratory has utilized LCV since 1993. Like luminol, the application of LCV to latent bloodstains creates a catalytic reaction with hemoglobin. Unlike luminol, however, the LCV reaction is visible in normal lighting. LCV stains latent blood a dark purple to black color allowing for easy observation and documentation on light colored surfaces. Bodziak does caution that visible bloodstains on fabric are best processed with DAB or Amido Black reagents. This research investigates the use of luminol and LCV to develop latent bloodstains from clothing, which has been washed with a commonly available cleaning product. A second aspect of this research was to test the use of the phenolphthalein as a presumptive blood test on the washed clothing items. A search of the major English language forensic journals and textbooks relating to bloodstain pattern analysis did not reveal any study that specifically examined the use of reagents on washed clothing. Quickenden et. al. (3) conducted research on the effectiveness of luminol in detecting washed bloodstains from automobile interiors. One interesting observation of their experiments was the conversion of hemoglobin to methemoglobin from increased heat in the motor vehicle following the deposition of blood. This resulted in and increased (enhanced) sensitivity of the luminol reaction. Not surprisingly, the authors discovered that repeated washings of interior surfaces decreased the sensitivity of the luminol reaction compared to non-washed surfaces. The authors did note, however, that the cleaning of carpet with a water and soap solution removed only the surface staining, leaving a strong presence within the foam padding of carpeting. Large quantitative differences in luminol reaction were observed between various carpet styles and commercial cleaning solutions however. Creamer et. al. (4) conducted research to determine the effect of the luminol reaction following the use of a known interfering catalyst (bleach) on washed items. The authors noted that luminol is highly sensitive, capable of detecting nanogram traces of blood. While their experiments were conducted on nonporous ceramic tiles, they observed that interference from bleach dissipated after approximately eight hours. DeHaan et. al. (5) also conducted sensitivity experiments with LCV on both porous and non-porous surfaces. Their research indicated LCV could detect blood at a dilution of 1:10,000, considerably less than luminol.